Biospheres

WaterSense with the Royal Tasmanian Botanical Gardens
12
Biospheres.. the forgotten art of terrariums
Biospheres...
the forgotten
art of terrariums
with Marcus Ragus
Terrariums
A biosphere
is a closed and self
regulating system, where
all the requirements for
life are included and no
other external ones are
required.
A terrarium is a planted jar, aquarium or clear container that contains soil,
water, plants and the gases oxygen and carbon dioxide which are required
for plant growth. Normally once a terrarium is made no other additions are
required; once the container is sealed a natural cycle of resources takes
place.
The terrarium had an accidental origin in the grimy and polluted dockland
area of East London. In 1829 Dr Nathaniel Bagshaw-Ward, a general
practitioner, keen amateur naturalist and fern collector was studying the
lifecycle of Hawk Moths using a small glass and lead greenhouse-like
container he had constructed. To his surprise, after a few days plants started
to grow in the moist compost that he had placed in the base of the container.
He soon realised that the moisture condensing each evening on the inside
of the glass container eventually ran down and watered the plants and that
the plants thrived, whereas outside in the polluted environment of London
similar plants grew poorly or died.
The containers became known as Wardian Cases and they ended up being
the main method of transporting live plants back and forth from exotic new
lands such as Australia.
In the mid to late 1990s the first human inhabited artificial biosphere was
built at a cost of over $200 million in the Arizona desert. Used in a series of
experiments it eventually became the base for the University of Arizona.
Making a terrarium
Terrariums are easy to make and because they are essentially closed systems
they don’t need a lot of water to keep them alive and lush; in fact they are
one of the most water efficient gardening techniques practiced.
To construct a terrarium you will first need a container that
can be sealed, has clear sides to allow light through and is
big enough to support some soil, and the plants you wish to
grow. Large glass jars and aquariums often make excellent
containers although you can also buy special glass feature
containers purposely made for terrariums at local retailers.
See the next page for a step-by-step guide on
making your own terrarium.
WaterSense with the Royal Tasmanian Botanical Gardens
Step 1: Starting out; arrange some larger rocks onto a
very thin layer of premium potting mix at the base of the
container. These will create a more natural mounded
effect and add structure and prevent slumping of the
potting mix over time.
Step 2: Add more potting mix around the rocks and
start your planting. It is really important to ensure that
the potting mix is moist to start with, which will negate
the need to water later. One of the major problems
people encounter with terrariums is that they often over
water to start with which leads to algae build up and the
eventual death of the plants.
Step 3: You can select a wide range of plants depending
on the type of environment you wish to create, usually
ferns, mosses and moisture loving plants are the easiest
to start with. Just remember to select plants that don’t
grow too large and that provide a range of interesting
Biospheres.. the forgotten art of terrariums
characteristics and habits such as coloured leaves, leaf
texture, ground covers, etc.
Step 4: Prepare your plants and plant them in the
potting mix you have already added to the terrarium.
Sometimes you may need tools such as a long handled
spoon, chopsticks or tongs to place the plants into
containers that have narrow access points. Try and
create a natural scene through strategic placement of
the plants. You can even use leaf size and shape to give
depth and perspective to your planted scene.
Step 5: Once the plants are
in, complete the surfaces of
the mix around the plants with
ground cover moss and some
feature pebbles or sand and
lightly water with a hand spray
mister. Don’t use a hose or
watering can as you only need
a little water and it is very easy
to overwater.
Step 6: Seal up your terrarium and place in a well lit,
natural light situation away from direct sun. Terrariums
do better if they have some ventilation, such as small
holes punched in the container lid or purposely built-in
vents.
To learn more about
WaterSense gardening, check
out the online videos at
www.rtbg.tas.gov.au or
taswater.com.au
Follow up every couple of months with a spray of water
and feed once a year with a light
scattering of a controlled release
fertiliser such as Osmocote™.